1. Field of Invention
The present invention relates as indicated to a reversing mechanism for use with handheld power tools in general and to an in line reversing gear mechanism for use with such power tools in particular.
2. Summary of Prior Art
In air power tools, the means most commonly relied upon to provide bidirectional or reversible rotation in a vane motor having two air inlet ports symetrically disposed in opposite halves of the vane motor chamber and a common exhaust port positioned midway between the inlet ports. Air entering one inlet port and exiting through the common exhaust port causes the air motor to rotate in one direction, whereas air entering the other inlet port and exiting the common exhaust port causes rotation of the motor in the opposite direction. This type of reversing air motor has several disadvantages. First, the air tool must include the valving necessary to alternately direct the pressurized air to one or the other of the two inlet ports. Second, the air must enter and exit the vane motor in something less than 180.degree. of movement. The expansive force and thus the power produced by the air motor is less than that which can be produced in a conventional single direction air motor wherein the radial separation of the inlet and outlet ports allows the effective utilization of the expansive power of the air over approximately 240.degree.. Thus, the output power of the tool must be compromised if a bidirectional air motor is to be utilized.
To avoid a bidirectional motor with the consequential loss of power, separate reversing mechanisms may be incorporated into a tool having a unidirectional motor. Examples of two different types of reversing mechanisms for this purpose are shown in Curtiss U.S. Pat. No. 4,274,304 and Ciolli U.S. Pat. No. 4,364,286, which patents are commonly assigned with the present application. These reversing mechanism are operationally satisfactory but include relatively complicated structure adding to manufacturing and assembling costs.